Optimum steady-state filter for periodic nonuniform sampling system

Diesel engine particulate certification, heretofore limited to on-highway truck engines, will be expanded in scope beginning in 1996. “Mini-dilution” tunnels have been the European and Japanese systems of choice for dilute particulate emissions certification for non-U.S. truck diesel engines. However, repeatability, steady-state test correlation versus full dilution systems, portability, sampling time, size, and system cost have precluded universal industry and regulatory acceptance of existing “mini-system” designs. To address corporate particulate measurement needs, the author developed a device known internally as the “Micro-Dilution Particulate Measurement System,” which meets the following objectives: (1) correlation with full dilution systems within ISO 8178 equivalency standards, (2) short sampling time, (3) reduced setup effort, and (4) excellent portability. Since the system is a true fractional sampler, it is insensitive to engine size, requiring only a simple stack probe change to provide accurate, representative steady-state diesel stack sampling on any size diesel engine.

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Error Analysis of a Quantitative Cerebral Blood Flow Measurement Using H215O Autoradiography and Positron Emission Tomography, with Respect to the Dispersion of the Input Function

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.1986.99 ◽

1986 ◽

Vol 6 (5) ◽

pp. 536-545 ◽

Cited By ~ 252

Author(s):

Hidehiro Iida ◽

Iwao Kanno ◽

Shuichi Miura ◽

Matsutaro Murakami ◽

Kazuhiro Takahashi ◽

...

Keyword(s):

Steady State ◽

Time Constant ◽

Input Function ◽

Inverse Laplace Transform ◽

Dispersion Function ◽

Sampling System ◽

Continuous Sampling ◽

Steady State Method ◽

Positron Emission ◽

Analytical Correction

The effect of the inaccuracy of the input function on CBF measured by the H152O autoradiographic method was investigated. In H152O autoradiography the measured input function usually includes a larger dispersion than the true input function, as well as the absolute time axis having been already lost. The time constant of the external dispersion that occurred in our continuous sampling system was evaluated as 10–12 s when the dispersion function was approximated by a monoexponential function. The internal dispersion occurring in arterial lines in a human body was evaluated as 4–6 s. Such dispersion, indispensable in a patient study, was found to produce large errors in calculating CBF, e.g., 5(10) s of the dispersion caused + 15(33) and + 10(20)% systematic overestimations for the 40- and 60-s accumulation time, respectively. An analytical correction employing an inverse Laplace transform was applied to clinical CBF studies, and the results were compared with those from the C15O2 steady-state inhalation method. Correction by 10 s in time constant, corresponding to the external dispersion, reduced the overestimation significantly from 70–100% to ∼20%. Further correction by 5 s, corresponding to the internal dispersion, resulted in a negligible difference (less than a few percent) from the steady-state method.

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Validation of continuous determination of respired gases during steady-state exercise

Journal of Applied Physiology ◽

10.1152/jappl.1975.38.4.736 ◽

1975 ◽

Vol 38 (4) ◽

pp. 736-738 ◽

Cited By ~ 4

Author(s):

G. W. Poole ◽

R. C. Maskell

Keyword(s):

Steady State ◽

Rapid Determination ◽

Linear Regression Analysis ◽

Sampling Technique ◽

Absolute Error ◽

Gas Analysis ◽

Sampling System ◽

Chemical Absorption ◽

Ventilation Rates

A continuous-flow sampling system (CFS) for convenient and rapid determination of respiratory gas exchange during steady-state exercise was described. CFS was compared to the classical bag collection system (BCS) by utilizing both methods concurrently during exercise for analysis of 32 1-min gas samples. The gas collected by BCS was analyzed by chemical absorption. The error in the gas mixing and sampling technique of CFS contributed to the absolute error of the gas analysis but did not adversely affect the reliability. The linear regression analysis on the data suggests that CFS is a relatively accurate and reliable system for use at light and moderate levels of steady-state work. However, it is hypothesized that unsteady-state conditions and heavy exercise, which elicits high ventilation rates, would compromise the accuracy and reliability of CFS. Therefore, it is recommended that the traditional BCS be utilized for determination of maximal oxygen uptake.

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Studies on Water in the Hydration Chamber of a Modified Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069715 ◽

1970 ◽

Vol 28 ◽

pp. 544-545

Author(s):

R. C. Moretz ◽

G. G. Hausner ◽

D. F. Parsons

Keyword(s):

Thin Film ◽

Thin Films ◽

Electron Microscope ◽

Steady State ◽

Room Temperature ◽

Small Mass ◽

Equilibrium Pressure ◽

Biological Objects ◽

Mechanical Pump ◽

Differential Pumping

Use of the electron microscope to examine wet objects is possible due to the small mass thickness of the equilibrium pressure of water vapor at room temperature. Previous attempts to examine hydrated biological objects and water itself used a chamber consisting of two small apertures sealed by two thin films. Extensive work in our laboratory showed that such films have an 80% failure rate when wet. Using the principle of differential pumping of the microscope column, we can use open apertures in place of thin film windows.Fig. 1 shows the modified Siemens la specimen chamber with the connections to the water supply and the auxiliary pumping station. A mechanical pump is connected to the vapor supply via a 100μ aperture to maintain steady-state conditions.

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Continuous hydrogenolysis of acetal-stabilized lignin in flow

Green Chemistry ◽

10.1039/d0gc02928a ◽

2021 ◽

Author(s):

Wu Lan ◽

Yuan Peng Du ◽

Songlan Sun ◽

Jean Behaghel de Bueren ◽

Florent Héroguel ◽

...

Keyword(s):

Steady State ◽

Challenges And Opportunities

We performed a steady state high-yielding depolymerization of soluble acetal-stabilized lignin in flow, which offered a window into challenges and opportunities that will be faced when continuously processing this feedstock.

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